Identification systems are utilized to obtain the identification (genus and species) of an organism. When the organism comes into contact with the substrates, the organism either reacts with the substrate (positive reaction) or there is no reaction (negative reaction). When the positive and negative reactions are combined, the identification of the organism is determined.

Susceptibility systems are utilized to determine what antimicrobics will be most effective in treating an organism. The organism is tested against various concentrations of antimicrobics, determining the organism's resistance (ineffective) or susceptibility (effective) to the antimicrobics. The identification and susceptibility of an organism is information that the physician requires from the laboratory, which is used when determining patient treatment.